Tuesday, November 9, 2010

USA Coral Snake Antivenom Update

Coral Snake (Micrurus sp) bites in North America are relatively rare. The last person to die from a coral snake bite in the USA was in 2006 when the victim did not seek treatment quickly because he was intoxicated. A second person bitten by the same snake survived the bite because he sought treatment and received the antivenom. The most recently made batch (Lot 403002) of North American coral snake antivenom was set to expire at the end of October 2010, but the U.S. Food and Drug Administration has extended the date to October 31, 2011 in the hope that another source of the antivenin can be found. On October 22, 2010 the FDA sent a note to health-care workers that contains the following statement.

"FDA has extended the expiration date on this lot of Antivenin (Micrurus fulvius) (Equine).  The extension is based upon FDA evaluation of stability data, which determined that this lot of product will maintain stability and potency for an additional year.

Wyeth Pharmaceuticals no longer manufactures Antivenin (Micrurus fulvius) (Equine).  There is no alternative product licensed in the U.S. for coral snake envenomations. Lot 4030026 is labeled with an expiration date of October 31, 2008.   Because this lot has a new expiration date, you may continue to maintain the product in your inventory and keep it available for use until October 31, 2011.  The manufacturer is updating the current labeling through a Dear Health Care Provider Letter.

Lot 4030026 continues to be available.  Wyeth is closely managing their inventory, and will supply product only to direct customers."

According to Sánchez, et al. (2008) coral snake bites compose less than 2% of total snakebites in most countries from southeastern United States to Argentina. In 2006, Wyeth Pharmaceutical notified customers that the production of the North American coral snake antivenin (NACSA) in the US was discontinued and adequate supplies were available to meet historical needs through the end of October 2008. They suggest that the logical alternative to replace the Wyeth product is the coral snake antivenom, Coralmyn, produced by the Mexican company, Bioclon. Sánchez et al. compared neutralization between the Wyeth and Coralmyn antivenoms with the North American coral snake venoms, the venom lethal doses (LD50) and antivenom effective doses (ED50) were determined in 18–20 g, female mice. They found Coralmyn antivenom was able to effectively neutralize three LD50 doses of all venom from both Micrurus tener tener and Micrurus fulvius fulvius, while the Wyeth antivenom only neutralized M. f. fulvius venom and was not effective in neutralizing three LD50 doses of M. t. tener venom. Therefore, Coralmyn is effective in the neutralization of both clinically important coral snake venoms in the USA.

Unfortunately, Bioclon has estimated it would take more than $5-10 million to research a new synthetic antivenom. Thus it would be cost prohibitive due to the small number of coral snake bites each year. This situation is just one more example of the dysfunctional nature of the American heatlthcare system.

Literature
FDA: http://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/ucm155092.htm

Sánchez, E. E., J. C. Lopez-Johnston, A. Rodríguez-Acosta and J. C. Pérez. 2008. Neutralization of two North American coral snake venoms with United States and Mexican antivenoms. Toxicon 51:297-303.

Snake Wine


After reading Ruchira and Nilusha Somaweeras' (2010) article on snake wine in Vietnam curiosity got the best of me. I Googled  “snake wine,” and  discovered that it is the name of a music album by a band named Light Pupil Dilate. However, I also found  plenty of websites touting the snake product, explaining its properties and selling it for substantial US dollars. My experience with snakes in wine bottles is restricted to one restaurant, located close to the National Science Museum in Thailand, that had several bottles on a shelf with cobras and unidentified colubrids. The Somaweeras’ article is of interest for several reasons. They documented the use of snakes in snake wine in four cities in Vietnam using surveys conducted at 127 locations selling the serpent beverages.  None of the species involved in the commerce were listed on the IUCN Red List, but seven species were listed in the Vietnam Red Data Book, of which five are regulated by CITES. The most abundant species used in the trade, was the natricid Xenochrophis flavipunctatus, a common snake that inhabits rice paddies and more natural wetlands, it made up 47% of the snakes identified. Perhaps the most significant finding of the surveys was the diversity of snakes used. The authors identified 1924 snakes composing more than 18 species (or species complexes) in eight different families. In my web search, a site called Thailand Unique contained the top photo at the left, and contained the following text (I have fixed a few spelling errors here).
  
Real Californian King Snake whiskey 50ml 37%v/v. This special whiskey (a.k.a. Rice Wine) is infused with a real farm raised Californian King snake, ginseng roots and other herbs. The whiskey is steeped for several months, which then imparts a unique flavour into the drink, giving it an acquired taste. In SE Asia it is believed to have aphrodisiac properties, however we make no claims to this. Every bottle is unique in its own way so therefore the item purchased may differ slightly in looks but not size.”

One look at the photo and it is clear that the snakes in the bottle never saw California or a farm, they are the Little File Snakes (Acrochordus granulatus), or sea snakes. They are clearly not California Kingsnakes.

Another interesting aspect of this project is that specific species are not being targeted by the industry. Instead, they appear to be using virtually any species available, thus the more common species are being harvested. Protecting wildlife from this kind of exploitation can only be solved through education. Laws are ineffective as deterrents to ideas from belief systems that have been around for thousands of years. 


Monday, November 8, 2010

Tianyusaurus, An Ancient Fruit-eating Lizard?


Several months ago I was watching a pair of tegu lizards (Tupinambis teguixin) feed on some over ripened mangos. It was quite messy, and the lizards walked away from the meal with mango smeared over their labial scales and faces. The macroteiids (family Teiidae) and microteiid lizards (family Gymnophthalmidae) are known only from the Western Hemisphere. Macroteiids are medium to large lizards that are omnivorous, Ameiva feed on fruits, but they seem to take insects more often; while the larger tegus are mostly predators and scavengers, but also opportunistic frugivores. The teiids are mostly Neotropical, but have expanded their distribution into North America (the Racerunners, Aspidoscelis); similarly the microteiids are Neotropical but without representation in North America. As their name suggest, they are tiny. Microteiids tend to be leaf liter swimmers with reduced limbs, consuming minute insects as they wiggle their bodies through grass or decomposing vegetation, but some are arboreal and semi-aquatic. The macroteiids are likewise diverse, several are semi-aquatic, while others are semi-arboreal, some inhabit tropical forests and savannas and yet others are desert-dwellers. In 2007, Randall Nydam and colleagues did a phylogenetic analysis that placed the fossil teiid-like lizards from the Cretaceous of Asia and North America in a new monophyletic group they named Boreoteiioidea and found it to be the sister taxon to the living Teiioidea (Teiidae + Gymnophthalmidae). Boreoteiioidea is from the Greek boreas, meaning north and is in reference to the northern hemisphere distribution of the Boreoteiioidea and the close relationship of this new taxon to Teiioidea. One implication of Nydam et al's work is that the macroteiids and microteiids have no pre-Tertiary fossils, and they suggested that Teiioidea and Boreoteiioidea diverged from a common ancestor by the Early Cretaceous, with the Teiioidea entering South America while the Boreoteiioidea radiated throughout North America and subsequently dispersed to Asia and Europe.

Tianyusaurus was described by Lü Junchanga and colleagues (2008) on the basis of a partial skeleton from a single individual (see photo). The remains were discovered in Upper Cretaceous sediments of the Qiupa formation in the Chinese province of Henan. In 2010, Mo et al. described three better preserved skulls that had been recovered from the 66 million year old Nanxiong formation in Jiangxi Province. Their phylogenetic analysis placed Tianyusaurus in the Boreoteiioidea. Of interest is the presence of a fully developed lower temporal bar and a fixed quadrate in Tianyusaurus, character states not associated with lizards (this has implications not discussed here), and suggest this lizard had a exceptionally large gape. Tianyusaurus teeth were also unusual, the premaxilla had 6–7 small teeth, the dentary had about 33 teeth and the maxilla had about 24 teeth. Surprisingly, the maxilla had large canine-like teeth with the teeth behind them compressed and expanded on the tips with crowns that had four cusps that were asymmetrical. The cusps on the dentary teeth were more symmetrical. The authors suggested that unlike other boreoteiioids with deep robust skulls and jaws used to crop tough plant material, Tianyusaurus ate something quite different; their food required a large gape and the ability to exert a penetrating force in the early stages of the bite. Mo, et al. hypothesized that Tianyusaurus ate turgid, fleshy fruits, an idea consistent with the differentiation of the upper and lower teeth and the exceptional gape. The asymmetrical upper teeth perforated the food with the apical cusp and then cut the food with the oblique cusped blade as the jaws close. The dentary teeth were shaped to hold the food in the mouth, so that the fruits would not slip out of the mouth.

Some angiosperms increased the size of their fruits in the Late Cretaceous, but other plant lineages like ginkgos, conifers, cycads, and seed ferns may also have had their seeds surrounded with fleshy tissue. The purpose of most fruits is to attract animals that will eat the fruit and the seeds it contains and carry them away from the parent plant so that the plant's embryos are dispersed. A few lizards do this today, but mostly its a service provided by endotherms (Tiffney, 2004).

Mo, et al. (2010) note that boreoteiioids are first reported in the Neocomian of Japan (about 130 MYA), represented by Kuwajimalla kagaensis a species that was about 130–150 mm in body length, and believed to have eaten foliage. Kuwajimalla had lanceolate denticulated teeth that are convergent with living Iguana teeth. Thus, Kuwajimalla kagaensis is the oldest known herbivorous squamate (Evans and Manabe, 2008) and suggests an Asian origin for the boreoteiioids, rather than the North American origin proposed by Nydam et al. Boreoteiioids represent the largest known radiation of herbivorous lizards, and the only Late Cretaceous clade of terrestrial lizards thought not to have survived the K-T extinction. 

Today, only 3% of living lizards are herbivorous, but this does not appear to have been the case in the past. Why so few living lizards are frugivorous, today is unclear, but it may be that they cannot compete with endotherms. Birds and mammals tend to be more mobile and capable of getting into trees and exploiting fruit before it falls to the ground and decomposes, and possibly before lizards can gain access to it. To the right are the teeth of two modern plant eating-lizards, the modern Iguana iguana and the Marine Iguana, Amblyrhynchus cristatus.




Literature

Evans S. E. and M. Manabe. 2008. A herbivorous lizard from the Early Cretaceous of Japan. Paleontology. 51:487–498.

Junchang Lü, Ji Shu'an, Dong Zhiming, Wu Xiaochun. 2008. An Upper Cretaceous lizard with a lower temporal arcade. Naturwissenschaften 95:663–669

Mo J, Xu X, Evans S. E. 2009. The evolution of the lepidosaurian lower temporal bar: new perspectives from the Late Cretaceous of South China. Proceeding of the Royal Society, Biological Sciences 277:331-336.

Nydam R. L., J. G.. Eaton, J. Sankey. 2007 New taxa of transversely-toothed lizards (Squamata: Scincomorpha) and new information on the evolutionary history of ‘teiids’. Journal of Paleontology. 81, 538–549.

Tiffney, B. H. 2004. Vertebrate dispersal of seeds through time. Annual Review of Ecology, Evolution and Systematics 35:1-29.


Sunday, November 7, 2010

Hamadryad Research


A number of recent papers have expanded out knowledge of the King Cobra, or Hamadryad, (Ophiophagus hannah), here a few that have appeared during 2010.

Bashir, et al. (2010) reports the sighting of the King Cobra from Yuksam village (27022’12.5’’N and 88013’27.0’’E). The village borders the Khangchendzonga Biosphere Reserve in the West District of Sikkim, India. The snake was observed in a drain adjoining human settlement (at an altitude of 1820 m) on 6 December 2009 at 0805 hr. The snake was estimated to be about 3−3.5 m. A few days later, the snake was seen basking on a rock near bamboo thickets adjoining the lake. There are two highlights: the new altitude record of 1840 m. for the northeast portion of the range; and, the fact that the snake was using the transitional forest between subtropical broadleaved evergreen forest and temperate forests. The species has not been previously reported from this Sikkim environment. Previously it was reported from Gangtok at 1700m in 1923 and was believed to be limited to the tropical forests of Sikkim Himalaya which are found below 1250 m. The highest known altitude record for the Hamadryad in northeastern India was 1700m at Khonoma, Nagaland (Das et al. 2008). 

Chen and Lai (2010) from the Guangzhou University of Chinese Medicine sequenced the complete mitochondrial genome of King Cobra (GenBank accession number: EU_921899) by Ex Taq-PCR, TA-cloning and primer-walking methods. The cobra’s genome is similar to other vertebrate. It is 17 267 bp in length and encodes 38 genes (including 13 protein-coding, 2 ribosomal RNA and 23 transfer RNA genes) and it contains two, long, non-coding regions. This data demonstrated that Elapidae is more closely related to Colubridae (=Colubroidae) than Viperidae, supporting previous work.

Zedoary (Curcuma zedoaria, family Zingiberaceae) is a plant native to South and Southeast Asia and it was introduced into Europe sometime in the sixth century, and while it is used as a spice it is rare, having been replaced by ginger. It is commonly used in the northeastern Thailand as a snakebite remedy. Lattmann, et al. (2010) isolated the active compound from the rhizome of C. zedoaroides, determined its structure and assessed its antagonistic properties against King Cobra venom. The acetone extract from the rhizomes of Curcuma rhizomes contained a C20 dialdehyde, as the major component. The isolated curcuma dialdehyde was to be found active in both in vitro and in vivo tests for antivenin activity against King Cobra venom. Using isolated rat phrenic nerve-hemidiaphragm preparations, the researchers found a significant antagonistic effect on the inhibition of neuromuscular transmission and muscle contractions were inhibited by the venom, and found they could reversed it with Curcuma dialdehyde in organ bath preparations over a period of 2 hours. Mice injected with 0.75 mg/kg venom and the dialdehyde had a significantly increased survival time. Injection of the Curcuma dialdehyde 30 minutes before the subcutaneous injection of the venom resulted in a 100% survival time after 2 h compared with 0% for the control group. Thus the in vitro and in vivo evaluation confirmed the medicinal use of Zedoary against King Cobra venom. 

Roy et al. (2010) have described haditoxin, a novel peptide from the venom of Ophiophagus. They provide a detailed structural and functional characterization of this unusual neurotoxin. Using a 1.5 Å crystal structure, they found haditoxin exists as a homodimer, similar to the κ-neurotoxin family, but the monomeric subunits of haditoxin, consist of a three-finger protein fold closely resembling a short-chain α-neurotoxins, unlike κ-neurotoxin monomers, which resemble long-chain α-neurotoxins. While haditoxin could antagonize several classes of nicotinic acetylcholine receptors in neurons and muscle, its greatest potency was against receptors, which neiher recognized by short-chain α-neurotoxins or κ-neurotoxins. Thus haditoxin might have many future uses in developing molecular probes and therapeutic agents.

Literature
Bashir, T., K. Poudyal, T. Bhattacharya, S. Sathyakumar & J.B. Subba, 2010. Sighting of King Cobra Ophiophagus hannah in Sikkim, India: a new altitude record for the northeast. Journal of Threatened Taxa 2(6): 990-991
.
Chen N. and X. P. Lai. 2010. [Sequencing and analysis of the complete mitochondrial genome of the King Cobra, Ophiophagus hannah (Serpents: Elapidae)] [Article in Chinese]. Yi Chan 32(7):719-25.

Lattmann, E., J. Sattayasai,, N. Sattayasai, A. Staaf, S. Phimmasone, C. H. Schwalbe, and A. Chaveerach. 2010. In-vitro and in-vivo antivenin activity of 2-[2-(5,5,8a-trimethyl-2-methylene-decahydro-naphthalen-1-yl)-ethylidene]-succinaldehyde against Ophiophagus hannah venom. Journal of Pharmacy and Pharmacology, 62:257–262. doi: 10.1211/jpp.62.02.0014

Roy, A., X. Zhou, M. Z. Chong, D. D'hoedt, C. S. Foo, N. Rajagopalan, S. Nirthanan, D. Bertrand, J. Sivaraman, and R. Manjunatha Kini. 2010. Structural and Functional Characterization of a Novel Homodimeric Three-finger Neurotoxin from the Venom of Ophiophagus hannah (King Cobra) Journal of Biological Chemistry 285: 8302-8315.

The Cypriot Grass Snake, Already Extinct?

A story carried by the Cypress Mail, written by Patrick Dewhurst (November 6, 2010) suggests the Cypriot Grass Snake (Natrix natrix cypriaca) will soon be extinct if it is not already. In an open letter to environmental Commissioner Charalambous Theopemptou, Hans George-Wiedl, a Cypress herpetologist and environmental activist, said he has not been able to find any signs of the snake in their last known habitat, the area around Paralimni Lake. Wiedl returned to the snake’s habitat for the first time in three years. He said, “I could see no sign of them, or any tracks left by them. The whole environment around the lake has changed for the worst. I would not be surprised if the grass snake at Paralimni has disappeared altogether… If there are a small number of grass snakes there, it is only a question of time until they disappear forever.”

The European Commission has required the Cyprus government ban real estate development in the area and designate the Paralimni a site of community importance (SCI).  While the government has made promises to do this, developments continued unabated. The Commission said it considered that “the Cypriot Authorities had not taken the necessary measures to protect the Cypriot Grass Snake, contrary to the requirements of directives on the conservation and habitats of flora and fauna.

A Reuters story from February 9, 2010, published in the Kathimerini, The International Herald Tribune in Greece and Cyprus reported that fishermen were being encouraged to once again fish the Xyialtos Reservoir, an area that had been off limits to them because they trampled the banks used by the Cyprus Grass Snake. This was an effort to reduce the introduced population of Largemouth Bass and trout. The invasive bass feeds in shallow waters near the banks of reservoirs; the same habitat used by Natrix natrix cypriaca  and . Both fish probably act as snake predators as well as competitors for food. The Cypriot Grass Snake rarely feeds on fish; most of its diet is composed of  Bedriaga's Frog, Pelophylax bedriagae (formerly Rana levantina).

Snakes of the genus Natrix on Cyprus have had a very confused history despite the fact that remains of Natrix natrix cypriaca were discovered at Aetokremmos, the oldest prehistoric site on Cyprus that dates to 12,000 YBP. The Grass Snake (Natrix natrix) was first reported from Cypress by botanist John Sibthorp when he visited the island in 1787, and the snake's presence was reaffirmed in 1865 when Unger and Koyschy noted its presence. Other reports of its presence were noted by Günther (1879) and by a variety of other authors and researchers. The flow of information about Cypriot Grass snakes stopped about 1913, although Hetch named the Cypriot population N. n. cypriaca in 1930 denoting its unique status as a Cypress endemic. By 1960 it was thought extinct but was rediscovered by Wield and  Böhme (1992).

Baier and Wield (2010) surveyed the population of N. n. cypriaca in the Troodos Mountains in 2008. Their results suggest that only two streams continue to be inhabited by the snake. The total number of Cypriot Grass Snakes in the Troodos area was estimated at 90–100 specimens. Suggesting there was a severe decline in the percentage of juveniles in both populations in comparison to studies in 2002 and 2005. 

A second species of natracid , the Dice Snake, Natrix tessellata, was also recorded from Cyprus by Unger and Kotschy (1865) and was also listed as part of the Cypriot fauna by other authors. Two subadult specimens of the Dice Snake (Natrix tessellata), collected in 1960 at Gönyeli-Nicosia, northern Cyprus, were discovered in the Zoological Collection of the Aegean University at Bornova-Izmir, Turkey by Göçmen, and Böhme. They challenged the view that the only existing voucher specimen of this species from Cyprus could have wrong locality data or was introduced to the island by humans. Thus, it seems the populations of both species of Natrix on Cypress are most likely near extinction.

Literature
Baier, F. and H.-J. Wiedl. 2010. The re-evaluated conservation status of the mountain populations of the highly endangered Cyprus Grass Snake, Natrix natrix cypriaca (Hetch, 1930), with miscellaneous natural history notes. Salamandra 46:1623.

Göçmen, B. and W. Böhme. 2002. New evidence for the occurrence of the Dice Snake, Natrix tessellata (Laurent, 1768) on Cyprus. Zoology in the Middle East 27:29–34.

Gunther, A. 1879. Notice of a collection of mammals and reptiles from Cyprus. Proceedings of the Zoological Society of London 1879:741.

Hecht, C. 1930. Systematik, Ausbreitungsgeschichte und Ökologie der europäischen Arten der Gattung Tropidonotus (Kuhl) H. Boie. – Mitteilungen aus dem Zoologischen Museum Berlin 16:244-393.
Wieldl, H. and W. Böhme. 1992. Wiederentdeckung der Ringelnatter (Natrix natrix ssp.?) auf Zypern, vorläufiger Bericht.  Herpetofauna 14:6-10.


Saturday, November 6, 2010

Cloud Cover, Basking, & Squamate Offspring

Basking turtles on logs, basking lizards on tree trunks, and basking snakes on the ground or at the water's edge are common sites. It is basking behavior that makes otherwise secretive reptiles most visible in their environments. While tropical species sometimes bask, temperate species do so more frequently because they are often in environments with daily changes in temperature that require them to raise their body temperatures for hunting, digesting food, finding mates and avoiding predators. Females of viviparous squamate reptiles also bask to regulate the temperature of their developing embryos. While the focus of climate change predictions is often on temperature, a warming climate also means increased humidity and increased cloud cover in some areas. In a forthcoming paper Kelly M. Hare and Alison Cree of the University of Otago, in New Zealand report on experimental manipulation of basking opportunities on gravid female McCann's Skinks (Oligosoma maccanni)and the impact basking time has on their offspring. Southern New Zealand, is predicted to undergo changes in mean annual air temperature over the next 100 years that are slightly below the average for global predictions, although predicted changes in cloud cover vary greatly. Cloud cover changes will alter basking opportunities at many locations, and the authors were interested in measuring the phenotypic consequences of  increased or reduced basking times experienced by the offspring of the viviparous, temperate skink. Female skinks were  housed in identical  containers, with a basking site and cool retreat site. Ambient room temperatures simulated a 1–2 °C increase in current mean day-time air temperatures as predicted under global warming scenarios, with 16-18 °C temperatures during the day and about 12 °C at night. When heat lamps were on, skinks could bask at their preferred temperature range or remain at room temperature They set-up three regimes for the lizards to bask. High basking females could bask  8 hours a day for 7 days a week,  mid-basking females could bask 5 days week–or 3.5 days week for a total of  56 or 40 hours (a regime similar to that used by females in the wild, low regime females could bask 28 hours per week.  The low regime group showed reduced success carrying embryos full term. After several late-stage abortions (nonviable offspring at near full-term/ development), the basking access of the remaining females was raised to 5 days week for the remainder of the pregnancy so that  viable offspring could be obtained for phenotypic study. They had 33 of the 51 females gave birth to 116 viable offspring. In addition, 15 stillbirths and nonviable embryos were obtained from eight of the 51 females. Measurements included: the sex, size, growth, survival, emergence behavior, morphotype, pigmentation, and locomotor performance of offspring up to 3 months of age. Most offspring characteristics were not influenced by the maternal basking regime. However, they found high cloud cover regimes lowered the success of pregnancy and female offspring grew more slowly, and were smaller. In McCann's Skinks, female offspring from the two warmer incubation regimes grew faster and attained significantly longer lengths than the other individuals. Like all lizards, female McCann Skinks must reach a minimum size before they are able to reproduce  and the increase in growth rate would potentially enable them to reproduce earlier and produce more offspring. Thus, changes in cloud cover have potentially long-term influences on population dynamics.

Literature
Hare, K. M. and A. Cree. 2010. Exploring the consequences of climate-induced changes in cloud cover on offspring of a cool-temperate viviparous lizard. Biological Journal of the Linnean Society. DOI: 10.1111/j.1095-8312.2010.01536.x

Friday, November 5, 2010

Snakebite Severity, Western Rattlesnake Venom, and Prey Digestion

In 2000,  I remember reading an article in Natural History Magazine that stunned me, the author was discussing the fact that rattlesnake bites were showing more neurotoxic symptoms, and that the reason for this was a gene or genes, that produced neurotoxin(s), was spreading through multiple species of US rattlesnake populations through hybridization. The implication was that some Mojave Rattlensnakes with neurotoxic venom were somehow moving cross-country and mating with members of other species of rattlesnakes. As crazy and improbable as this hypothesis is, it was picked up by media and may have fueled  further speculation by physicians in the southwest who reported increases in the number of severe snakebite cases in recent years. William Hayes and Steve MacKessy (2010) have recently addressed this issue and note a greater number of articles that suggest snakes are evolving more toxic venom, perhaps in response to human activity in the environment. Hayes and MacKessy propose other explanations that are more probable and include factors dependent on the snake and factors associated with the bite victim’s response to envenomation. They suggest that while bites could become more severe from an increased proportion of bites from larger or more provoked snakes (ie, more venom injected) that venom evolves slowly, much too slowly, to account for a rapid increase in  the severity of symptoms. The severity of a bite can be influenced by many factors including the demographics of the snakebite victims. So, changes in age, body size, behavior toward the snake (provocation), anatomical site of the bite, clothing (or lack of it), as well as overall general health of the snakebite victim are important. Allergies have increased in the population in recent years, and this may be an overall indicator of the populations' changing sensitivity to foreign antigens. Hospital care of bites has also changed, making comparisons of snakebite severity over time difficult. Media coverage of atypical bites and accompanying speculation has been misleading and is likely to raise public anxiety about snakes.


In a second article,  but one related to the discussion above, MacKessy (2010) examined the venom from the eight subspecies of the the Western Rattlesnake (Crotalus oreganus-viridis species complex ). The Western Rattlesnakes are widely distributed across the western half of North America and while some venom characteristics have been noted for most subspecies there has been no systematic study of venoms from all subspecies. MacKessy extracted venom from all eight Western Rattlesnake snake subspecies collected in the approximate geographic center of their range. The venom was analyzed using  mass spectrometry, enzyme and toxicity assays and electrophoretic. The results demonstrated that small myotoxins, disintegrins and PLA2 were abundant in most venoms and; PIII and PI metalloproteinases were common to all venoms except  the Midget Faded Rattlesnake, the Northern Pacific Rattlesnake, and the Southern Pacific Rattlesnake (C. o. concolor, C. o. caliginis and C.o. helleri). Metalloproteinase activity was highest in the Arizona Black Rattlesnake (C. o. cerberus) and lowest in the Midget Faded Rattlesnake (C. o. concolor) venoms (with a 100-fold difference). Conversely, the Midget Faded Rattlesnake (C. o. concolor) venom was the most toxic and Arizona Black Rattlesnake (C. o. cerberus) venom was least toxic (a 15-fold difference). Overall, MacKessy found  venoms with high metalloproteinase activity were less toxic (type I venoms), while venoms which were highly toxic showed low protease activity (type II venoms). Within the Western Rattlesnake species complex, both extremes of venom composition occur  and it appears that high metalloproteinase activity and high toxicity are incompatible qualities of these venoms. So why are there such dramatic differences in the biochemical characteristics of these related rattlesnakes? likely relates to characteristics of prey consumed, and venoms with low metalloproteinase activity may constrain snake prey selection or foraging activity patterns. Metalloproteinases are common and abundant in viper venoms and contribute significantly to the occurrence of hemorrhage and necrosis following envenomation.  An important role of
 venom has been assumed to be prey digestion, and the metalloproteinases have been implicated as the major family of proteins involved in digestion. However, a more recent study indicated that at 30°C digestive efficiency was not enhanced by venom and that the role of venom in digestion is, indeed, minimal. At this higher temperature, it is not surprising that venom has little effect, another study suggests temperature dependence of venom-enhanced digestion has a highly pronounced effect at cooler temperatures and minimal effect at higher temperatures. Snake gastric processes are highly efficient at “normal operating temperatures,” but venom metalloproteinases likely provide the additional degrading enhancement which facilitates efficient digestion of the prey at the suboptimal temperatures encountered in the field.

Snake venom evolves in response to hunting success or failure. Venom that quickly incapacitates a specific prey species, or venom that starts digestion in cooler than normal environments will be favored over venom that is less efficient. As prey evolves resistance to venom the snake will evolve venom that is more toxic and more efficient, or be less successful and not pass on its genetic material. It seems highly improbable humans are having any impact on venom evolution - other than possibly pushing its source to extinction.

Literature
Grenard S. 2000. Is rattlesnake venom evolving? Natural History 109:44–46.

Stephen P. Mackessy 2010. Evolutionary trends in venom composition in the Western Rattlesnakes (Crotalus viridis sensu lato): Toxicity vs. tenderizers. Toxicon,  55:1463-1474

William K. Hayes and Stephen P. Mackessy. 2010. Sensationalistic Journalism and Tales of Snakebite: Are Rattlesnakes Rapidly Evolving More Toxic Venom? Widerness and Environmental Medicine 21:35–45.

Thursday, November 4, 2010

Cordylid Lizard Fossils, Phylogeny, and Sensitivity to Climate Change

The saurian family known as the Girdled Lizards (Cordylidae) has about 80 species with common names like, Armadillo Lizards, Sungazers, and Flat Lizards. They are mostly rock-dwelling scinciform lizards that have at least some dermal armor. Living members are endemic to Sub-Saharan Africa and have been traditionally placed in four  genera: the Flat Lizards, Platysaurus with exceptionally depressed bodies; the African Grass Lizards, Chamaesaura, reduced limb species with long tails; the Crag Lizards, Pseudocordylus, crevice-dwelling lizards; and the Armadillio Lizards of the genus Cordylus, heavily armored species. But, there are fossil species known from the early to middle Miocene of Europe: Palaeocordylus bohemicus and Bavaricordylus ornatus.  Böhme (2010) has reported on the fossil species at Sandelzhausen Germany, a site that produced remains of several cordylids. The Miocene of Sandelzhausen had a quite different climate than it does today. It was semi-arid to sub-humid, with 571-847 mm of mean annual precipitation making it subtropical with mean annual temperatures ranging from 18°C to 20.8°C, mean cold month temperatures as high as 13.3°C and mean warm month temperatures as high as 28.1°C.

A recent molecular study has produced a new view of the cordylids. Stanley et al. (2010) used three nuclear and three mitochondrial genes from 111 specimens, representing 51 of the 80 known taxa and recovered a comb-like tree with 10, well-supported, monophyletic lineages.Their taxonomic reassessment divides the family into 10 genera that correspond to the well-supported lineages. They recovered evidence that supports two subfamilies within the Cordylidae, the egg-laying Platysaurinae and the live-bearing Cordylinae. A preliminary dating analysis place the diversification of the Cordylinae between 35 and 25 million years ago, during the Oligocene a period when southern Africa would have been cool and dry. This may explain why these lizards evolved viviparity, one hypothesis suggests the ability to bear live young is an adaptation to cold environments, allowing the live-bearing female to carefully regulate the temperature of the developing embryos by shuttling between warm and cool microhabitats. The authors found that the reproductive strategies of the two cordylid subfamilies are consistent with this pattern, the viviparous cordylines inhabit temperate areas, at higher altitudes and higher latitudes, while the oviparous platysaurines are restricted to the tropics and subtropics. The Oligocene was cool and dry and may have been an ideal environment for the cold-adapted, rock-dwelling, stem cordylines.

The challenges lizards face from a warming planet was recently examined by Tolley (2010), she reviewed recent research and specifically addressed the cordylids because they are rock dwelling species, and rocks heat rapidly and cool slowly. Thus, the Cordylidae could be more susceptible to temperature increases than ground-dwelling or arboreal lizards because their microhabitats would be unusable for longer periods of time. The situation for cordylines may be worse than other lizards because viviparous lizards are thought to be more sensitive to temperature changes and believed twice as likely to go extinct as egg-laying species. Extinctions are not predicted to be high for members of the Cordylidae at present, nor over the next 40 years, but their risk of extinction is expected to increase by the year 2080.

Literature
Böhme, M. 2010. Ectothermic vertebrates (Actinopterygii, Allocaudata, Urodela, Anura, Crocodylia, Squamata) from the Miocene of Sandelzhausen (Germany, Bavaria) and their implications for environment reconstruction and palaeoclimate. Paläontologische Zeitschrift, 84:3-41, DOI: 10.1007/s12542-010-0050-4.

Stanley, E. L., A. M. Bauer, T. R. Jackman, W. R. Branch and P. Le Fras N. Mouton. 2010. Between a rock and a hard polytomy: Rapid radiation in the rupicolous girdled lizards (Squamata: Cordylidae)
Molecular Phylogenetics and Evolution, doi:10.1016/j.ympev.2010.08.024.

Tolley, K. A. 2010. Can lizards beat the heat, or will they go extinct? South African Journal of Science 2010;106(5/6), 2 pages. DOI: 10.4102/sajs. v106i5/6.278. This article is available at: http://www.sajs.co.za



Wednesday, November 3, 2010

Boa Constrictor Produces Viable WW Offspring Via Parthenogensis

Faculative parthenogensis has been previously reported in numerous families of squamates. In some lizards parthenogenic species results from hybridization. Female snakes, isolated in captivity from males,have produced offspring asexually. It has generally been thought that females fertilize their own eggs using the secondary polar body produced during the second division of meiosis. The polar body is haploid (N) and therefore could act as a sperm by contributing a complete set of chromosomes to the offspring. Snakes normally have a ZW sex chromosome system, males are ZZ, females are ZW, and offspring that would receive the chromosome combination WW, would be females but were believed not to survive development (this would be similar to having a YY male in mammals). However, WW females have been experimentally produced in the lab in fish and amphibians. Today, Warren Booth of the University of North Carolina and colleagues have published an early on-line article that describes a female boa constrictor producing two litters of all female offspring that were WW, and the female had been housed with males. In an interview with the BBC Booth told the reporter, "The female [boa] has had not one virgin birth, but actually two, in spite of being housed with and observed to be courted by multiple males. All offspring are female. The offspring share only half the mother's genetic make-up..." The researchers used microsatellite DNA fingerprinting, to document the first evidence of facultative parthenogenesis in the Boa constrictor and identified multiple, viable, non-experimentally induced females for the first time in any vertebrate lineage. They hypothesized in the paper that the elevated homozygosity of the offspring in relation to the mother may be the product of terminal fusion automixis (fusion of the secondary polar body to the egg nucleus). The fact that no males were produced suggests maternal sex chromosome hemizygosity (WO) - that is the female had only one sex chromosome, and when the chromosome replicated, the sister chromosomes did not separate (non-disjunction). This report is the first evidence of parthenogenesis in the family Boidae and suggest that WW females may be more common within basal reptilian lineages than previously assumed.

Booth, W., D. H. Johnson, S. Moore, C. Schal and E. L. Vargo. 2010. Evidence for viable, non-clonal but fatherless Boa constrictors. Biology Letters published online 3 November 2010. doi: 10.1098/rsbl.2010.0793.

Fossorial Eyes

Many fossorial squamates in many different lineages have evolved reduced eyes. In the early 20th century Gordon Walls proposed that an ancestral snake went through a burrowing phase, lost or reduced their eyes, and then re-evolved larger, functional eyes when they adapted again to life on the surface. A variety of hypotheses have been proposed to explain eye-reduction in fossorial squamates and other animals, including: a lack of  a need to respond predators, sudden changes in environmental conditions, or visual accuracy. Exceptionally small eye balls have been said to have evolved to save metabolic energy, or atrophy in fossorial habitats, or reduced due to developmental anomalies. Pressure placed on the eyeballs as the animal burrows through soil has also been considered the cause of the reduction. Foureaux et al. (2010) examined  the eyes of four species of fossorial reptiles: three amphesbaenids (Amphisbaena alba, Amphisbaena mertensi, Leposternon infraorbitale) and the blind snake Typhlops brongersmianus (family Typhlopidae). Using a light microscope, as well as an SEM the authors visualized the minuscule eyes and did histological examinations. Although small, and generally considered to be degenerated, the 1–2 mm diameter eyes were covered with a thin, transparent scale that covers a conjunctival sac and corresponds to the spectacle of other snakes. The Blind Snake's eyes were oval, while the amphisbaenids' eyes were cup-shaped. The amphisbaenids' sclera was composed of cartilage, while the Typhlops' sclera was composed of connective tissue and striated muscle fibers. The retina of these fossorial species had all of the layers found in other vertebrates. Reduction in the size of the eyeball, the rudimentary cornea, an absence of the anterior chamber, the presence of a complex iris-ciliary body, and a lens with amorphous nucleate cells all correlate with a fossorial life style. The fact that the retina was intact and presumably functional suggests that the eyes of fossorial squamates may in fact function for light perception.

Foureaux, G., M. I. Egami, C. Jared, M. M. Antoniazzi, R. C. Gutierre, R. L. Smith. 2010. Rudimentary Eyes of Squamate Fossorial Reptiles (Amphisbaenia and Serpentes).The Anatomical Record 293(2)351–357.

Tuesday, November 2, 2010

Fossils + DNA Produce a New Squamate Tree


Molecular data and fossil data, when examined separately may differ in providing information on how groups of species are related to each other. But molecular data offer great potential to resolve the phylogeny of living taxa, particularly those that lack a fossil record. Weins et al. ask the question can molecular data improve our understanding of relationships of fossil taxa? They analyze the placement of snakes within the Squamata by combining published morphological data (363 characters) and new DNA sequence data (15,794 characters, 22 nuclear loci) for 45 living and 19 fossil taxa. The results suggest some fossil taxa undergo major changes in their phylogenetic position when molecular data are added; most fossil taxa are placed with strong support in the expected clades by the combined data Bayesian analyses, despite each having substantial numbers of missing cells and despite the recent suggestions that extensive missing data are problematic for Bayesian phylogenetics; that morphological data can change the placement of living taxa in combined analyses, even when there is an overwhelming majority of molecular characters. Also, they discovered a strong but misleading signal in the morphological data with respect to snakes, amphisbaenians, and dibamids; presumably this is due to limblessness and a fossorial life style. Of particular interest here is the position of snakes as the sister to the Anguimorphs. With the Anguimorpha consisting of the extinct marine reptiles, the Mosasauria, the monitor lizards, the heloderms, and the anguids. Within the snakes, the South American fossil species Dinilysia is the sister to all of the other snakes except the scoleocophidians, and the fossil species with hind limbs (Eupodophis, Haasiophis, Pachyrhachis) plus the Australian fossil species Wonambi are the sisters to the macrostomate snakes.

Wonambi usually considered a member of the extinct Madtsoiidae that first appears in the fossil record in late Cretaceous and extends to the late Pleistocene. The fossil family members have been found in South America, Africa, India, Southern Europe, and Australia. Madtsoiidae are known for a long, narrow skull; that are relatively inflexible upper jaws; a rounded snout; a braincase that narrows at the orbit and widens posteriorly,and elogated vertebrae. To date no evidence of hind limbs have been found.Wonambi reached an estimated length of 18 ft.

Dinilysia patagonica is known from the Cretaceous of Argentinia, South America  and is considered closely allied to the extant anilioid snakes. Dinilysia is often compared to booids and it had a relatively large head, and is thought to have been terrestrial. Comparisons of the cranial anatomy of Dinilysia to the recently described hind-limbed, Argentine Gondwanan snake, Najash rionegrina suggest similarities in the two species, but hind limbs have not been found in Dinilysia. The evidence for a Gondwanaland origin of snakes is relatively strong.


John J. Wiens, Caitlin A. Kuczynski, Ted Townsend, Tod W. Reeder, Daniel G. Mulcahy, and Jack W. Sites, Jr. 2010. Combining Phylogenomics and Fossils in Higher-Level Squamate Reptile Phylogeny: Molecular Data Change the Placement of Fossil Taxa. Systematic Biolology  doi:10.1093/sysbio/syq048

Monday, November 1, 2010

More on La Nina and Snakes in Queensland

Queensland's Daily Mercury is carrying the following story regarding increased snake activity due to the La Ninia Climate. See the earlier post that discussed this.
City's crawling with snakes
Cait Bester

While many humans are cursing an extremely wet spring and subsequent warm weather our slithering friends have been making the most of it – rearing their heads in places they aren’t invited.

Snake experts are blaming La Nina for increased snake numbers this season.

Mackay’s Australian Wildlife Rescue Service snake catcher Matthew Moon caught a coastal carpet python in a Slade Point family’s guinea pig cage last week; earlier in the week – in the middle of the night – Mr Moon rescued a brown tree snake, also known as a night tiger, from the Wood Street taxi rank. They are two of Mackay’s most commonly found snakes.

“We have to hand in a log of how many snakes we have caught in a three-month period and when I handed my book in at the beginning of September I had 30 callouts for snakes,” Mr Moon said.

“Since September, I already have had 23 callouts and we are expecting the number to increase as the weather gets warmer.

“There are a lot of snakes on the move at the moment and even back in July I was collecting snakes.

“I can say there are a lot more than normal and we are putting it down to the weather patterns we have been experiencing.”

Mr Moon said it wasn’t uncommon to come across brown snakes and pythons in new estates where there were no trees.

“I am getting more and more callouts to new housing estates, which once were cane land,” he said. “While there are no trees around there is still a large food supply for them.”

Animals are not the only snake victims – 62 people having been treated at the Mackay Base Hospital emergency department for snake bites this year.

With an increase in snake activity snake experts have urged residents to be on the lookout for the creatures.

“If you come across a snake you are best to leave it alone. If you frighten them that is when they will react and will either bite or end up in the house,” Mr Moon said.

“People should contact me and I will come and collect the snake for them and I will then release them back into the wild.

If you come across a snake and need it removed Mr Moon can be contacted on 0413 072 892. Or call the Australian Wildlife and Rescue Service on 0447 543 268.

There is a $20 callout fee.

China's Consumption of Snakes and Almost Everything Else

MinnPost.com posted the following story today.
China's dangerous appetite for rare animals
By Kathleen E. McLaughlin

GUANGZHOU, China — The teenaged cook grabs a handful of slim green snakes from their cage outside the kitchen, seizing them by their necks as he wields his cleaver in the other hand. In a matter of minutes, he slits the skin of each snake from neck to tail, the squirming reptiles still alive and moving in a frenzy as they’re dropped into a wok.

In a matter of one hour, the snakes will be eaten, plates cleaned by local businessmen along with glasses of beer and rice wine. The small creatures, believed to have been smuggled into China from Vietnam, are among tens of thousands of protected and endangered animals illegally trafficked across China’s borders to feed an ever-growing appetite.

It seems that for many, the best way to demonstrate new wealth and power in China is to eat something rare, something potentially illegal. Nowhere is this better witnessed than in Guangzhou, capital of Guangdong province.

“Guangdong is a semi-tropical climate and they once had a lot of wild animals, so the custom of eating wild animals is very strong,” explained Fang Minghe, head of a citizen environmental watchdog group called Green Eyes. “In recent years, Guangdong’s economy has developed very well. People here are rich and things are expensive, and wild animals are becoming table luxuries that are sold for very high prices.”

In the same restaurant, a cobra lounges warily in a cage next to the kitchen, waiting for some diner to seal his fate. The staff won’t say where he came from, but an environmental group that monitors the wildlife trafficking industry in Guangzhou says it is almost certain that the regal, three-foot-long snake was brought into China illegally or under hazy circumstances.

Environmental groups have stepped up their efforts in recent years to monitor and report on China’s illegal wildlife trade, seeking to stop the ever-increasing smuggling of rare and endangered animals. But their efforts thus far have not matched the power of China’s growing wealth boom.

The numbers are staggering. According to Traffic, a wildlife trade monitoring organization, China’s borders are “hot spots” for this illicit business. Estimates vary, but the illicit animal trade is believed to be worth more than $10 billion annually in China. The trade kills protected bears, tigers, snakes, turtles, fish and just about anything that has or once had a pulse.

In the city’s traditional medicine market, hundreds of vendors peddle banned animal parts along with their legal herbs and potions, most notably, the flesh and scales of the pangolin — a critically endangered Southeast Asian anteater that is being driven to the brink of extinction by Chinese demand.

While most rare animal consumption in China seems targeted at male virility, the medicine vendors say the pangolin’s main purpose is to improve the health and breast milk of new mothers. But pangolin flesh is being sacrificed into near oblivion for pure human pleasure. Locals laugh that Guangzhou residents are known for wanting to eat “strange foods” — the stranger, the better.

According to one study, as many as 50,000 pangolins lived wild in China in 2000. They are now gone, and China has started draining its neighbors of the needle-nosed creatures, with smugglers bringing in thousands every year from Vietnam, Myanmar, Indonesia and Malaysia. One restaurant in Ruili, a small city hundreds of miles from here on Myanmar's border with China, is known for offering pangolin on the menu.

Most recently, Africa has become a provider of smuggled animal parts to feed the Chinese hunger. In recent years, the ivory trade has boomed in China — particularly in Guangzhou, where even the airport has a shop that sells nothing but ornate carvings made from elephant tusks. The lobby of one five-star hotel in the city center showcases a massive carving depicting life in the Song Dynasty, using dozens of elephant tusks and priced at around $10 million. Officials contend that the vast majority of China’s emergent ivory trade is legal, but critics say the spike in demand for legally traded ivory has increased smuggling — a notion bolstered by recent busts.

Environmentalists and experts are reluctant to level any criticism at the local government or border patrol for the problem. In fact, most won’t discuss it openly at all. But those who do say the local and central governments are increasingly aware this is a problem that must be dealt with. The question, they say, is whether officials will step up enforcement and clamp down corruption on the borders quickly and efficiently enough to save the species that China gobbles up.

Groups like Fang’s Green Eyes have taken to working within the system, depending on volunteer armies of college students and young workers to police local restaurants and markets and report violations to the border police. But Fang admits that full-scale reform is needed to change the trafficking and demand. China managed to save the Great Panda from the brink of extinction, and it now has the money and resources to save less symbolic species.

“Right now, wild animals are a dead subject in China,” Fang said. “Maybe in another 10 years, things will be different.”

Amphibians and Reptiles of Northeast India, A Photographic Guide: A Book Review





Ahmed, M. F., A. Das, and S. K. Dutta. 2010. Amphibians and Reptiles of Northeast India, A Photographic Guide. Guwahati: Aaranyak. 169 pages. About US$25.

There are many places on the globe that have a poorly known herpetofauna, while these places are fewer in number than they were 50 years ago, they still exist. Northeast India  covers 2.6 million square kilometers, and is composed of the political units of: Assam, Arunachal Pradesh, Meghalaya, Nagaland, Manipur, Mizoram, Tripura and Sikkim. It contains portions of the Eastern Himalayan and Indo-Burma Biodiversity Hotspots and has a species rich herpetofauna with some of the most spectacular species of the planet's fauna. Here you can see the unique crocodilian, the Gharial (Gavialis gangeticus); the Narrow-headed Softshell Turtle (Chitra indica) one of the largest freshwater turtles; the Burmese Python (Python bivittatus); the Reticulated Python (Broghammerus reticulatus); as well as many colorful rhachophorid frogs, pit vipers, and cobras. The book covers 101 species with accounts and those species are illustrated in 165 color photos. An additional 90 species are illustrated in the back of the book in a Photo Gallery Appendix. Thus, the book contains illustrations of about 70% of the 274 species of the herpetofauna known to occur in Northeast India. Sections on: how to use the guide, conservation, an introduction to amphibian and reptiles, snakebite management and first aid, facts and fallacies, and indexes are included. Each species account is contained on a single page with a high quality photograph of the species. The text for each account included a diagnostic synopsis, distribution, habits and habitat; diet, legal protection, conservation status and threats, and notes. Overall this is an excellent book that will provide the user with easily accessed information on much of the herpetofauna of Northeast India. The book will be useful for the ecotourist or the visiting herpetologist who may not be familiar with the fauna, as well as the local population. The volume is a great start for a region that has been poorly known.
The book is available from Aaranyak ,50, Samanwoy Path, Survey, Beltola, Guwahati- 781028, Assam, India, email: info@aaranyak.org

Fox Snakes, Garter Snakes and Habitat Fragmentation

Roads, housing, and agriculture tend to fragment habitats and how this impacts wildlife, particularly reptiles is not fully understood. DiLeo et al. (2010)  investigated the effects of the fragmented landscapes of Southwestern Ontario, Canada on the genetic population structure of the eastern garter snake (Thamnophis sirtalis sirtalis) and the Eastern Fox Snake (Mintonius [Elaphe] gloydi) which are sympatric, but have distinct habitat preferences. The garter snake is a habitat generalist, while the fox snake is marsh specialist, is rarer, and is geographically restricted.  They used DNA microsatellite markers to examine genetic population structure of both species. Genetic clusters were overlaid on a habitat map to deduce possible physiognomic barriers to gene flow.  The results showed three genetic clusters for garter snakes and five for Fox Snakes. Each garter snake had a near equal probability of membership to two or more clusters with no cluster suggesting garter snakes comprise a single genetic population. Fox Snake, however, clustered to geographical  locations on the landscape, that roughly correlated with isolated patches of suitable habitat. The results suggest  fox snakes and garter snakes are impacted in different ways by the same landscape fragmentation or they may have dramatically different effective population sizes. Agricultural areas and roads separate existing populations of fox snakes and appear to be barriers to gene flow, while garter snake are unrestricted by these features. The authors suggest that fox snakes are more susceptible to habitat fragmentation than garter snakes and that they could benefit from having their patches of habitat connected by riparian corridors

Michelle F. DiLeo, Jeffrey R. Row and Stephen C. Lougheed. 2010. Discordant patterns of population structure for two co-distributed snake species across a fragmented Ontario landscape. Diversity and Distributions 16:571–581.